Deposition method, deposition apparatus, and structure

ABSTRACT

A deposition method includes: introducing a gas into an airtight container containing electrically insulated raw material particles to generate an aerosol of the raw material particles; transferring the aerosol to a deposition chamber through a transfer tubing connected to the airtight container, the deposition chamber having a pressure maintained to be lower than that of the airtight container; injecting the aerosol from a nozzle mounted on a tip of the transfer tubing toward a target placed on the deposition chamber to cause the raw material particles to collide with the target, thereby causing the raw material particles to be positively charged; generating fine particles of the raw material particles by discharge of the charged raw material particles; and depositing the fine particles on a substrate placed on the deposition chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 14/626,220, filed on Feb. 19, 2015, which claims the benefit under35 U.S.C. § 119 of Japanese Patent Application No. 2014-130348, filedJun. 25, 2014, and Japanese Patent Application No. 2014-258652, filedDec. 22, 2014, which are herein incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

The present disclosure relates to a deposition method and a depositionapparatus that use an aerosol gas deposition method, and to a structureprepared using the method.

An aerosol gas deposition method in which submicron-sized particles ofceramic or the like are injected from a nozzle at ambient temperatureand are deposited on an opposite substrate has been known. Thisdeposition method is being used at present in wide application fieldssuch as thin film preparation and thick film preparation.

The applicant of the subject patent application has already proposed adeposition method that is capable of forming a dense film using fineparticles having a relatively large particle diameter (see WO2012/081053 and Japanese Patent Application Laid-open No. 2014-9368).This deposition method causes raw material fine particles to be chargedby friction with the inner surface of a transfer tubing and deposits thecharged fine particles on a substrate while transferring an aerosol to adeposition chamber. With this method, it is possible to reliably form afilm having an excellent density and adhesiveness.

BRIEF SUMMARY

In recent years, it is an important development item to improve theinsulating properties and adhesiveness of a coating film in designing oflaminated device, in a field of thin-film electronic device, forexample. In particular, a thin coating film having a high dielectricstrength is expected to be developed.

In view of the circumstances as described above, it is desirable toimprove the density and adhesiveness of a formed film and to provide adeposition method and a deposition apparatus that are capable of formingan insulating film having a high dielectric strength even if theinsulating film is thin, and a structure including such an insulatingfilm.

According to an embodiment of the present disclosure, there is provideda deposition method including introducing a gas into an airtightcontainer containing electrically insulated raw material particles togenerate an aerosol of the raw material particles. The aerosol istransferred to a deposition chamber through a transfer tubing connectedto the airtight container, the deposition chamber having a pressuremaintained to be lower than that of the airtight container. The aerosolis injected from a nozzle mounted on a tip of the transfer tubing towarda target placed on the deposition chamber to cause the raw materialparticles to collide with the target, thereby causing the raw materialparticles to be positively charged. Fine particles of the raw materialparticles are generated by discharge of the charged raw materialparticles. The fine particles are deposited on a substrate placed on thedeposition chamber.

The above-mentioned deposition method forms a film by causing an aerosolof raw material particles injected from a nozzle to collide with atarget to cause the raw material particles to be positively charged,generating fine particles of the raw material particles by discharge ofthe charged raw material particles, and causing the fine particles toenter and collide with the substrate. The discharge of the raw materialparticles typically generates plasma of the gas in the depositionchamber, in the vicinity of the target. In the plasma, cations of gasmolecules sputter the surface of incoming (neutral) particles and thus,nano-sized particles are generated.

The substrate is typically connected to a ground potential. Many of thefine particles are electrically charged. The charged fine particles areattracted to the substrate by electrical interaction with the substrate,and are deposited with electrostatic adsorption with the surface of thesubstrate. Therefore, a dense coating film having an excellent adhesiveforce to the substrate is formed. On the other hand, electricallyneutral raw material particles having a relatively large particlediameter do not reach the surface of the substrate and are ejected tothe outside of the deposition chamber through the gas stream. In thisway, nano-sized particles of the raw material particles are deposited onthe substrate. Accordingly, a dense insulating film having a highadhesiveness is formed on the substrate.

The material constituting the raw material particles is not particularlylimited. For example, various insulating materials such as alumina(aluminum oxide), aluminum nitride, and barium titanate are used. Inaddition, the raw material particles may have a structure in which aninsulating film is formed on the surface of a conductor. The particlediameter of the raw material particles is not also particularly limited.For example, raw material particles having a particle diameter of notless than 0.1 μm and not more than 10 μm are used.

These raw material particles are positively charged by collision withthe target, and can generate discharge between the particles and thesubstrate maintained at ground potential.

In the deposition chamber, the substrate is arranged on an axis linethat passes through an irradiation surface of the target to which theaerosol is applied and is in parallel with the irradiation surface.Accordingly, it is possible to introduce the raw material particlescharged by collision with the irradiation surface onto the substratethrough gas flow. As a result, it is possible to form a dense film notincluding raw material particles having a large particle diameter butincluding raw material particles having a fine particle diameter.

Moreover, by reciprocating the substrate in the in-plane directionduring deposition, it is possible to form a coating film in a desiredarea on the surface of the substrate.

As the material constituting the target, a metal material such asstainless steel and copper or a conductive material such as graphite canbe used. These conductive materials are likely to be negatively chargedas compared with the raw material particles. Therefore, it is possibleto effectively cause the raw material particles to be positivelycharged.

The gas introduced into the airtight container has a function togenerate an aerosol of the raw material particles and a function as acarrier gas to transfer the raw material particles to the depositionchamber. As such a gas, nitrogen, argon, or the like, is typically used.However, a mixed gas obtained by mixing any one of these gases withoxygen may be used, or only oxygen may be used.

Because argon has a lower discharge voltage than nitrogen, theefficiency of sputtering the raw material particles is improved.Accordingly, it is possible to improve the deposition rate.

In the case where the raw material particles include an oxide, oxygendefect tends to be generated due to the sputtering operation of ions inplasma. Under the presence of oxygen, however, oxygen defect of the rawmaterial particles is reduced. Accordingly, it is possible to ensure theoxygen concentration in the film and to form a thin film having anexcellent dielectric strength, for example.

According to an embodiment of the present disclosure, there is provideda deposition apparatus including a generation chamber, a depositionchamber, a transfer tubing, a target, and a stage. The generationchamber is configured to be capable of generating an aerosol of rawmaterial particles. The deposition chamber is configured to be capableof having a pressure maintained to be lower than that of the generationchamber. The transfer tubing is configured to connect the generationchamber and the deposition chamber and include a nozzle configured toinject the aerosol at an end portion thereof. The target is arranged inthe deposition chamber, has an irradiation surface that is irradiatedwith the aerosol injected from the nozzle, and is configured to causethe raw material particles to be positively charged by collision of theraw material particles with the irradiation surface. The stage isconfigured to support a substrate on which fine particles of the rawmaterial particles generated by discharge of the charged raw materialparticles are deposited, the substrate being arranged on an axis linethat passes through the irradiation surface and is in parallel with theirradiation surface.

According to the present disclosure, it is possible to form a coatingfilm having a high density and adhesiveness.

These and other objects, features and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram of a deposition apparatusaccording to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram for explaining the operation of thedeposition apparatus;

FIG. 3 is a schematic configuration diagram of a deposition apparatusaccording to a comparative example;

FIG. 4 is a schematic diagram showing the structure of a film formed bya deposition method according to a comparative example;

FIG. 5 is a schematic diagram showing the structure of a film formed bya deposition method according to an embodiment of the presentdisclosure;

FIG. 6 is a TEM image showing the boundary area between a substrate andan alumina fine particle film deposited by using the depositionapparatus; and

FIG. 7 is a schematic diagram of an apparatus for explaining anexperimental example of the embodiment.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure will be describedwith reference to the drawings.

Deposition Apparatus

FIG. 1 is a schematic configuration diagram of a deposition apparatusaccording to an embodiment of the present disclosure. The depositionapparatus according to this embodiment constitutes an aerosol gasdeposition (AGD) apparatus. In FIG. 1, X-axis, Y-axis, and Z-axisdirections represent triaxial directions orthogonal to each other, andthe Z-axis direction represents a vertical direction (the same shallapply to the following figures).

As shown in FIG. 1, a deposition apparatus 1 includes a generationchamber 2, a deposition chamber 3, and a transfer tubing 6. An aerosolof raw material particles P is generated in the generation chamber 2,the deposition chamber 3 contains a substrate S on which a depositionprocess is performed, and the aerosol is transferred from the generationchamber 2 to the deposition chamber 3 through the transfer tubing 6.

The generation chamber 2 and the deposition chamber 3 are formedindependently, and the internal spaces of the chambers are connected toeach other through the inside of the transfer tubing 6. The depositionapparatus 1 includes an evacuation system 4 connected to the generationchamber 2 and the deposition chamber 3, and is configured to be capableof evacuating the respective atmospheres of the chambers to apredetermined reduced pressure atmosphere and maintaining theatmosphere. The generation chamber 2 further includes a gas supplysystem 5 connected to the generation chamber 2, and is configured to becapable of supplying a carrier gas to the generation chamber 2.

The generation chamber 2 contains the raw material particles P beingaerosol raw materials, and an aerosol is generated therein. Thegeneration chamber 2 is connected to a ground potential, and is formedof an airtight container including glass, for example. In addition, thegeneration chamber 2 includes a lid portion (not shown) for taking inand out the raw material particles P. The deposition apparatus 1 mayfurther include a vibration mechanism that vibrates the generationchamber 2 to agitate the raw material particles P or a heating mechanismthat degasses (removes water or the like of) the raw material particlesP.

The raw material particles P are aerosolized in the generation chamber2, and is deposited on the substrate S in the deposition chamber 3. Theraw material particles P include fine particles formed of a materialbeing a deposition target. In this embodiment, as the raw materialparticles P, alumina (aluminum oxide) fine particles are used.

It should be noted that other than that, other electrically insulatedceramic particles such as aluminum nitride and barium titanate can beapplied to the raw material particles P. Moreover, the raw materialparticles P may have a structure in which an insulating film is formedon the surface of a conductor. The particle diameter of the raw materialparticles P is not particularly limited. For example, those having aparticle diameter of not less than 0.1 μm and not more than 10 μm areused.

In the deposition chamber 3, a stage 7 that is configured to hold thesubstrate S is movably arranged. Outside the deposition chamber 3, astage drive mechanism 8 that is configured to move the stage 7 isprovided. The stage drive mechanism 8 is configured to be capable ofreciprocating the stage 7 in a direction in parallel with the depositionsurface of the substrate S at a predetermined speed in the depositionchamber 3. In this embodiment, the stage drive mechanism 8 is configuredto be capable of moving the stage 7 linearly along the X-axis direction.

The substrate S includes glass, metal, ceramic, a silicon substrate, orthe like. The AGD method can form a film at ambient temperature, and isa physical deposition method without a chemical process. Therefore, itis possible to select various materials as the substrate. Moreover, thesubstrate S is not limited to a flat substrate, and may be athree-dimensional substrate.

The deposition chamber 3 and the stage 7 are each connected to a groundpotential. The stage 7 may include a heating mechanism that isconfigured to degas the substrate S before deposition. Moreover, in thedeposition chamber 3, a vacuum gauge that designates the internalpressure may be provided. The deposition chamber 3 is maintained at apressure lower than that of the generation chamber 2.

The evacuation system 4 is configured to vacuum-evacuate the generationchamber 2 and the deposition chamber 3. The evacuation system 4 includesa vacuum piping 9, a first valve 10, a second valve 11, and a vacuumpump 12. The vacuum piping 9 includes a branch piping that connects thevacuum pump 12, the generation chamber 2, and the deposition chamber 3to each other. The first valve 10 is arranged between the branch pointof the vacuum piping 9 and the generation chamber 2, and the secondvalve 11 is arranged between the branch point of the vacuum piping 9 andthe deposition chamber 3. The configuration of the vacuum pump 12 is notparticularly limited. For example, the vacuum pump 12 includes amultiple stage pump unit. The multiple stage pump unit includes amechanical booster pump and a rotary pump.

The gas supply system 5 is configured to supply a carrier gas to thegeneration chamber 2. The carrier gas defines the pressure in thegeneration chamber 2 and is used to generate an aerosol. As the carriergas, N₂, Ar, He, O₂, dry air, or the like, is used. The gas supplysystem 5 includes gas pipings 13 a and 13 b, a gas source 14, thirdvalves 15, gas flowmeters 16, and a gas injection body 17. The thirdvalves 15 are arranged in the gas pipings 13 a and 13 b. The gasflowmeters 16 are arranged in the gas pipings 13 a and 13 b.

The gas source 14 includes a gas cylinder, for example, and isconfigured to supply a carrier gas. The gas source 14 is connected tothe gas injection body 17 through the gas piping 13 a. The gas piping 13b is formed by branching from a gas piping 13, and the tip of the gaspiping 13 b is arranged in the generation chamber 2. The carrier gassupplied to the generation chamber 2 through the gas piping 13 a ismainly used to roll up the raw material particles P. The carrier gassupplied to the generation chamber 2 through the gas piping 13 b ismainly used to control the gas pressure in the generation chamber 2.

The gas injection body 17 is arranged in the generation chamber 2, andis configured to uniformly inject the carrier gas supplied from the gaspiping 13. The gas injection body 17 may be a hollow body in which manygas injection holes are provided, for example, and is arranged at aposition where the gas injection body 17 is covered by the raw materialparticles P, e.g., at the bottom of the generation chamber 2.Accordingly, it is possible to efficiently roll up the raw materialparticles P by the carrier gas, and to aerosolize it. The gas flowmeter16 is configured to designate the flow rate of the carrier gas flowingthrough the gas pipings 13 a and 13 b. The valve 15 is configured to becapable of adjusting the flow rate of the carrier gas flowing throughthe gas pipings 13 a and 13 b and blocking the carrier gas.

The transfer tubing 6 is configured to use the internal pressuredifference between the generation chamber 2 and the deposition chamber 3to transfer the aerosol generated in the generation chamber 2 to thedeposition chamber 3. One end of the transfer tubing 6 is connected tothe generation chamber 2. The other end (tip portion) of the transfertubing 6 is arranged in the deposition chamber 3, and includes a nozzle18 configured to inject an aerosol. The transfer tubing 6 and the nozzle18 are connected to a ground potential.

The nozzle 18 includes a metal material such as stainless steel. Theinner surface of the passage of the nozzle 18 through which an aerosolpasses may be covered by a carbide material. Accordingly, it is possibleto reduce attrition due to collision with the fine particlesconstituting the aerosol, and to improve the durability. Examples of thecarbide material include titanium nitride (TiN), titanium carbide (TiC),tungsten carbide (WC), and diamond-like carbon (DLC).

The inner surface of the transfer tubing 6 is formed of a conductor. Asthe transfer tubing 6, a linear metal pipe such as a stainless pipe istypically used. The length and inner diameter of the transfer tubing 6can be appropriately set, and are 300 mm to 2000 mm and 4.5 mm to 24 mm,respectively, for example.

The opening shape of the nozzle 18 may be a circular shape or a slotshape. In this embodiment, the opening shape of the nozzle 18 is a slotshape, and the length of the opening is not less than 10 times and notmore than 1,000 times as large as the width of the opening. In the casewhere the ratio of the length to the width of the opening is less than10 times, it is difficult to effectively cause particles to be chargedin the nozzle. On the other hand, in the case where the ratio of thelength to the width of the opening exceeds 1,000 times, the amount ofinjected fine particles is limited and the deposition rate issignificantly reduced although the efficiency of charging particles isimproved. The ratio of the length to the width of the nozzle opening isfavorably not less than 20 times and not more than 800 times, morefavorably, not less than 30 times and not more than 400 times.

The deposition apparatus 1 further includes a target 19 connected to aground potential. The target 19 is arranged in the deposition chamber 3,and is configured to be capable of causing the raw material particles Pto be charged by collision with the aerosol injected from the nozzle 18.Specifically, the deposition apparatus 1 according to this embodiment isconfigured to cause an aerosol of the raw material particles P injectedfrom the nozzle 18 to collide with the target 19 to cause the rawmaterial particles P to be charged, to generate nano-sized fineparticles (nanoparticles) by discharge of the charged raw materialparticles P, and to deposit the generated nanoparticles on the substrateS.

The charging of the raw material particles P causes a gas component inthe deposition chamber 3 to emit light, i.e., generates plasma, andsputters the surface of the raw material particles P in the plasma togenerate nanoparticles. Many of the generated nanoparticles areelectrically charged. The nanoparticles are attracted by the substrate Sconnected to a ground potential, and collide with the substrate S whilebeing deposited on the substrate S with electrostatic adsorption withthe surface of the substrate S (see an arrow A1 in FIG. 2). Accordingly,a dense film that includes fine particles and has a high adhesiveness isformed on the substrate.

On the other hand, electrically-neutral raw material particles having arelatively large particle diameter do not reach the substrate S and areejected to the outside of the deposition chamber 3 through the gasstream (see an arrow A2 in FIG. 2). In order to efficiently form such agas stream, an end portion 91 of the vacuum piping 9 connected to thedeposition chamber 3 is favorably provided on a side wall on theopposite side of a side wall of the deposition chamber 3 to which thetransfer tubing 6 is inserted.

The target 19 typically includes, but not limited to, a flat plate. Thetarget 19 may include a bulk body having a block shape, a pillar shape,or a spherical shape. An irradiation surface 190 that is irradiated withan aerosol is not limited to a flat surface and may be a curved surfaceor a concavo-convex surface.

As the material constituting the target 19, a material that is likely tobe negatively charged as compared with the raw material particles P istypically used. Specifically, in the case where the raw materialparticles P include alumina particles, a material that is on thenegative side of the triboelectric series as compared with the aluminaparticles is favorable. Examples of such a material include stainlesssteel, copper, an alloy thereof, aluminum, an alloy thereof, aconductive material such as graphite, a semiconductor material such assilicon, and a mixture including at least two of them. In addition, thetarget 19 may include a laminated body obtained by bonding such amaterial to the surface of the above-mentioned bulk body.

The target 19 is arranged to be inclined with respect to the nozzle 18by a predetermined angle so that the aerosol injected from the nozzle 18enters the target 19 at a predetermined incidence angle (angle betweenthe normal line direction of the irradiation surface 190 and theincident direction of the aerosol). The incidence angle is not less than10 degrees and not more than 80 degrees, for example. In the case wherethe incidence angle is less than 10 degrees or exceeds 80 degrees, it isdifficult to effectively cause the raw material particles P to becharged. By setting the incidence angle of the aerosol with respect tothe target 19 to be in the above-mentioned range, it is possible todeposit the raw material particles. Moreover, in the case where the rawmaterial particles include alumina particles, the incidence angle is setto be more than 30 degrees and less than 70 degrees, for example, andmore favorably, not less than 45 degrees and not more than 65 degrees.Accordingly, it is possible to improve the efficiency of charging theraw material particles P, to effectively reduce the size of the rawmaterial particles P to a nano-level size, and to form an alumina filmhaving an excellent dielectric strength. The target 19 may be rotatablyplaced in the deposition chamber 3 so that the incidence angle can bevaried.

The distance between the nozzle 18 and the target 19 is not particularlylimited, and is not less than 5 mm and not more than 50 mm, for example.In the case where the distance is less than 5 mm, the influence of theinteraction between particles positively charged on the target 19 andthe nozzle 18 (outer surface of the tip portion is negativelyquasi-charged) is large, and flying of the charged particles to thesubstrate is possibly inhibited. On the other hand, in the case wherethe distance exceeds 50 mm, the speed of the raw material particlesinjected from the nozzle 18 is attenuated, and effective collision ofthe particles with the target 19 and effective charging of the particlesare possibly reduced. Moreover, because the range of the aerosolinjected from the nozzle 18 is expanded, the target 19 needs to beincreased in size in some cases. The target 19 may be movably placed inthe direction in which the aerosol is injected in the deposition chamber3 so that the distance can be varied.

The stage 7 (substrate S) is arranged on an axis line 191 that passesthrough the irradiation surface 190 of the target 19 and is in parallelwith the irradiation surface 190. Specifically, the stage 7 is arrangedat a position that is not on an extension of the direction in which theraw material particles injected from the nozzle 18 are regularlyreflected on the irradiation surface 190 of the target 19. Accordingly,it is possible to prevent raw material particles that have a relativelylarge particle diameter and are pulverized by collision with theirradiation surface 190 and the material constituting the target 19flies out of the irradiation surface 190 due to sputtering of the rawmaterial particles P injected from the nozzle 18 from reaching thesubstrate S (see an arrow A3 in FIG. 2). As a result, it is possible toform a dense film that includes no raw material particle having a largeparticle diameter nor material constituting the target 19, but includesraw material particles having a fine particle diameter.

The irradiation surface 190 of the target 19 is arranged to be inclinedwith respect to the direction of the normal line of the surface of thestage 7 (substrate S) by a predetermined angle. In the case where theraw material particles include alumna particles, the predetermined angleis set to be more than 30 degrees and less than 70 degrees, and morefavorably, not less than 45 degrees and not more than 65 degrees. Theangle of the irradiation surface 190 with respect to the stage 7(substrate S) may be set to the same angle as the incident angle of theaerosol with respect to the target 19 or an angle different from theincidence angle.

The distance between the stage 7 and the target 19 (distance between thecollision point of the aerosol on the irradiation surface 190 and thesurface of the stage 7 along the Z-axis direction) is not particularlylimited, and is not less than 5 mm, for example. In the case where thedistance is less than 5 mm, the target 19 is sputtered by ions in plasmagenerated on the surface of the substrate S and the materialconstituting the target 19 is possibly mixed in the film. The distanceis favorably set to not less than 10 mm.

Deposition Method

Next, a deposition method according to this embodiment will be describedwith reference to FIG. 2. FIG. 2 is a schematic diagram for explainingthe operation of the deposition apparatus 1. Hereinafter, a method ofdepositing an alumina film using the deposition apparatus 1 will bedescribed.

A predetermined amount of raw material particles P (alumina powder) isplaced in the generation chamber 2 first. A degassing/dehydratingprocess may be applied to the raw material particles P by heating inadvance. Alternatively, by heating the generation chamber 2, thedegassing/dehydrating process may be applied to the raw materialparticles P. By degassing/dehydrating the raw material particles P, itis possible to prevent the raw material particles P from agglomeratingand to increase the amount of charged raw material particles P byfacilitating drying.

Next, the evacuation system 4 evacuates the generation chamber 2 and thedeposition chamber 3 to a predetermined reduced atmosphere. Theoperation of the vacuum pump 12 is started, and the first valve 10 andthe second valve 11 are opened. When the pressure in the generationchamber 2 is sufficiently reduced, the first valve 10 is closed and thedeposition chamber 3 is evacuated continuously. The generation chamber 2is evacuated together with the deposition chamber 3 via the inside ofthe transfer tubing 6. Accordingly, the deposition chamber 3 ismaintained at a pressure lower than that of the generation chamber 2.

Next, the gas supply system 5 introduces a carrier gas into thegeneration chamber 2. Each of the third valves 15 of the gas pipings 13a and 13 b is opened, and the carrier gas is injected in the generationchamber 2 from the gas injection body 17. The carrier gas introducedinto the generation chamber 2 increases the pressure in the generationchamber 2. Moreover, as shown in FIG. 2, the carrier gas injected fromthe gas injection body 17 causes the raw material particles P to fly,and the raw material particles P float in the generation chamber 2.Thus, an aerosol (represented by A in FIG. 2) including the raw materialparticles P dispersed in the carrier gas is formed. The generatedaerosol A flows to the transfer tubing 6 due to the difference betweenpressures in the generation chamber 2 and the deposition chamber 3, andis injected from the nozzle 18. By adjusting the degree of opening ofthe third valve 15, the formation state of the aerosol A and thedifference between pressures in the generation chamber 2 and thedeposition chamber 3 are controlled.

The difference between pressures in the generation chamber 2 and thedeposition chamber 3 is not particularly limited, and is not less than10 kPa and not more than 180 kPa, for example. In the case where thedifferential pressure is less than 10 kPa, the deposition rate is low,which causes a trouble in practical use. On the other hand, in the casewhere the differential pressure is more than 100 kPa, the generationchamber 2 needs to have a pressure resistant structure with respect toan applied pressure. Specifically, because a glass container is notsuitable as a pressurized container, it needs to use a stainless steelcontainer having a pressure resistant structure, for example. Thedifferential pressure may be further high. However, the differentialpressure up to 180 kPa is favorable from a viewpoint of practical use,taking into account the regulation of a high pressure gas.

The aerosol (represented by A′ in FIG. 2) that has flowed to thetransfer tubing 6 is injected at a flow rate defined by the openingdiameter of the nozzle 18 and the difference between pressures in thegeneration chamber 2 and the deposition chamber 3. The irradiationsurface 190 of the target 19 is irradiated with the aerosol of the rawmaterial particles P injected from the nozzle 18. The raw materialparticles P positively charged by collision or friction with theirradiation surface 190 discharge between the raw material particles Pand the irradiation surface 190 or gas molecules in the vicinity of theirradiation surface 190, and plasma of the carrier gas is generated. Thesurface of the raw material particles P is sputtered by plasma, andthus, the raw material particles P are reduced in size. Accordingly,nano-sized fine particles having a size of not less than 5 nm and notmore than 25 nm are generated, for example. Many of the generated fineparticles are electrically charged, and are electrostatically attractedby the substrate S on the stage 7 connected to a ground potential towardthe substrate S connected to a ground potential along the axis line 191as shown in an arrow A1 in FIG. 2. The fine particles may grow oragglomerate until the fine particles reach the substrate S. When thefine particles reach the surface of the substrate S, the fine particlescollide with the surface of the substrate S and are brought into closecontact with the surface of the substrate S with electrostaticattraction with the substrate S. Accordingly, a dense fine particle film(alumina film) having an excellent adhesiveness is formed.

On the other hand, most of neutral raw material particles that are notcharged are introduced into an exhaust vent of the deposition chamber 3(the end portion 91 of the vacuum piping 9) through the gas streamrepresented by an arrow A2 in FIG. 2, and ejected to the outside of thedeposition chamber 3 without reaching the substrate S. Therefore, it ispossible to deposit only nano-sized fine particles on the substrate Swithout mixing coarse particles in the film.

Furthermore, raw material particles regularly reflected on theirradiation surface 190 of the target 19, the material constituting theirradiation surface 190 sputtered by the raw material particles, or thelike flies through a path represented by an arrow A3 in FIG. 2, and isattached to the inner wall of the deposition chamber 3, for example,without reaching the substrate S. Therefore, it is possible to preventcoarse raw material particles, the material constituting the target 19,and the like from mixing in the coating film on the substrate S.

It should be noted that when the fine particles of the charged rawmaterial particles P reach the substrate S, a discharge phenomenon withlight emission is caused on the surface of the substrate S in somecases. Also in this case, the fine particles are further broken bysputtering in plasma, and the particles are deposited on the substrate.Accordingly, it is possible to further improve the density andadhesiveness of a film.

The stage 7 is reciprocated at a predetermined speed along the in-planedirection of the substrate S by the stage drive mechanism 8.Accordingly, it is possible to form a coating film in a desired area ofthe surface of the substrate S. In this embodiment, because the stage 7is reciprocated in parallel with the X-axis direction, i.e., the gasflow direction, a thickness distribution in which the film thicknessincreases as the distance from the target 19 increases is achieved.Accordingly, an interference fringe of light caused due to thedifference of the film thickness is observed in the deposition areaafter deposition in some cases.

FIG. 3 is a schematic configuration diagram of a deposition apparatus100 according to a comparative example. Hereinafter, the depositionmethod according to this embodiment will be described in comparison withthe deposition method using the deposition apparatus 100.

It should be noted that in FIG. 3, the same components as those in FIG.1 will be denoted by the same reference symbols and a descriptionthereof will be omitted.

The deposition apparatus 100 shown in FIG. 3 is different from thedeposition apparatus 1 according to this embodiment in that thedeposition apparatus 100 does not include the target 19. Specifically,the deposition apparatus 100 according to the comparative example isconfigured so that the nozzle 18 is arranged at a position that facesthe substrate S on the stage 7 and an aerosol A′ injected from thenozzle 18 is directly applied to the surface of the substrate S.

FIG. 4 is a schematic diagram showing the structure of a film depositedby the deposition apparatus 100 according to the comparative example.

A film F1 deposited by the deposition apparatus 100 according to thecomparative example has a relatively high adhesive force to thesubstrate S. However, because various raw material particles P1 havingdifferent particle sizes are mixed in the film F1, many spaces areformed between the particles. This is considered because a method ofdirectly spraying an aerosol to the substrate S to form a film is usedand thus, fine powder generated by sputtering of raw material powderhaving an original particle size or raw material particles charged byfriction with the inner surface of the nozzle due to discharge betweenthe powder or particles and the substrate is deposited concurrently.Therefore, it is difficult to improve the density of a formed film.Furthermore, it may be impossible to ensure a stable film qualitybecause the density of the film varies.

On the other hand, the deposition method using the deposition apparatus1 according to this embodiment applies an aerosol to the target 19 once.Therefore, it is possible to improve the efficiency of charging the rawmaterial particles P. Accordingly, the amount proportion of charged fineraw material particles to the raw material particles that have reachedthe substrate increases, and it is possible to deposit uniformnano-sized particles P2 (having a particle diameter of not less than 5nm and not more than 15 nm, for example) on the substrate S as shown inFIG. 5. In this way, it is possible to form a dense film F2 with a fewspaces between the particles while ensuring the adhesiveness to thesubstrate S.

Moreover, according to this embodiment, the dispersibility of eachparticle increases because nanoparticles generated by the sputteringphenomenon in the vicinity of the surface of the target 19 and thesubstrate S are deposited on the substrate S. Accordingly, it ispossible to form a film having a uniform particle size distribution onthe substrate S.

In order to improve the deposition rate, it is favorable to improve theefficiency of charging the raw material particles or use a type of gashaving a low discharge voltage as a carrier gas. This is because theefficiency of generating ions increases as the discharge voltage isreduced, thereby improving the efficiency of sputtering the raw materialparticles and facilitating generation of the fine particles. Typicalexamples of the gas having a low discharge voltage include argon. Byusing argon, it is possible to reduce the discharge voltage as comparedwith a gas such as nitrogen.

Moreover, in the case where the raw material particles include an oxide,oxygen defect tends to be caused due to the sputtering of ions inplasma. In this case, the insulating properties of a formed film arereduced, and it is difficult to reliably form an oxide thin film havinga desired dielectric strength. By mixing an oxidized gas such as oxygen(e.g., 5% or more) in the carrier gas or using the oxidized gas as thecarrier gas, it is possible to reduce oxygen defect caused due to thesputtering operation of plasma. Accordingly, it is possible to ensurethe oxygen concentration in the film and to form a thin film having anexcellent dielectric strength, for example.

On the other hand, the pressure of the carrier gas affects generation ofplasma, i.e., generation of discharge. If there is no gas component(high vacuum), plasma in the state where a plus ion and an electroncoexist is not maintained. In this regard, in this embodiment, the flowrate of the carrier gas is set so that the pressure of the depositionchamber 3 is not less than 50 Pa and not more than 3 kPa, for example.Accordingly, it is possible to reliably generate and maintain plasma,and to reliably deposit a film having a uniform particle size.

Furthermore, the raw material particles P1 may be heated at atemperature of not less than 300° C. under vacuum in the generationchamber 2 before an aerosol is generated. Accordingly, it is possible tofacilitate desorbing of adsorbing water or bonding water of the rawmaterial particles P1 and of carbonic acid adsorption to optimize theconcentration and friction charge amount of the transferred raw materialparticles P1 by gas. Moreover, because the raw material particles P1 isheated under vacuum in a container for generating an aerosol, it ispossible to generate an aerosol without exposing the raw materialparticles P1 to the atmosphere after the desorbing process.

Formed Film

It is an important development item in designing of a laminated deviceto increase the insulating properties of a coating film in order to puta thin film electronic device into practical use. It is desired to forma thin coating film having a high dielectric breakdown electric fieldintensity. For example, alumina is a material having insulatingproperties and a low-dielectric constant (low-k), and the dielectricbreakdown electric field intensity of the bulk of alumina is 100 to 160kV/cm. In order to produce a fine thin film device, for example, analumina insulating film needs to have a thickness of not more than 10 μmand a resistance voltage of not less than 3 kV. The dielectric breakdownelectric field intensity corresponds to not less than 3 MV/cm beingabout 20 times as large as that of the bulk body.

It is considered that in the structure where fine ceramic nanoparticlesare densely bonded, the insulation resistance is theoretically higherthan that of the bulk body due to increase in the number of bondinginterfaces. In order to achieve a dielectric breakdown electric fieldintensity higher than that of the bulk body, there is a need to form acoating film in which nanoparticles having a remained structure aredensely coupled. Moreover, it is necessary to reduce the temperature inthe deposition process to cause the nanoparticles to remain.

The deposition method according to this embodiment generates plasma byapplying an aerosol of raw material particles, as described above, andachieves charging of raw material particles and size reduction ofnanoparticles by sputtering with discharge. Accordingly, as shown inFIG. 5, it is possible to obtain the coating film F2 being anaggregation film of the nano-sized crystalline particles P2. It goeswithout saying that in the film, particles finer than the crystallineparticles P2 or particles that are slightly larger than the crystallineparticles P2 may be mixed. It has been confirmed that in the case wherea film is formed with alumina raw material particles having an averageparticle diameter of 0.5 μm, the average particle diameter of thecrystalline particles P2 is not less than 5 nm and not more than 25 nm.

Therefore, the density of the film formed on the substrate S isequivalent to that obtained not only by the deposition method accordingto the comparative example but also by another thin film formationmethod such as a CVD method and a sputtering method. According to thisembodiment, it is possible to form an alumina film having a dielectricbreakdown electric field intensity that is not less than 10 times aslarge as that of the bulk body. In particular, a formed alumina thinfilm is confirmed to have a film thickness of 0.5 μm and a dielectricbreakdown electric field intensity of not less than 3 MV/cm. This valuecorresponds to 20 times of that of the bulk body. Furthermore, thedeposition rate is 20 times as high as that in the sputtering method.Furthermore, according to this embodiment, it is possible to reliablydeposit a highly-resistive insulating film having a direct currentelectrical resistance of not less than 1×10¹¹Ω and not more than1×10¹²Ω.

Moreover, in the deposition method according to this embodiment,electrostatic adsorption operation on the surface of the substrate S (ora fine particle film formed on the surface) rather than mechanicaladhesion operation obtained by collision of the raw material fineparticles with the surface of the substrate S dominates on the coatingfilm F2 formed on the surface of the substrate S. The surface of thesubstrate S is a uniform surface before and after the deposition.Therefore, it is possible to prepare a structure in which the coatingfilm F2 having an excellent adhesiveness is formed on the surface of thesubstrate S without forming an anchor portion deformed in aconcavo-convex shape by collision with the raw material fine particles.FIG. 6 is a TEM image showing the boundary area between a siliconsubstrate and an alumina fine particle film formed thereon.

Moreover, the alumina thin film formed by the deposition methodaccording to this embodiment has a high transparency, and can be appliedto a heat insulation coating film including a glass material in thearchitectural industry or automobile industry, for example, with asynergetic effect of high toughness and high heat insulating propertiesof alumina. Moreover, in the electronics industry, information andcommunication industry, aerospace industry, and the like, a thin aluminainsulation film having a high intensity and a high dielectric breakdownvoltage can be applied to the outside coating in order to furtherdownscale a chip component. Furthermore, a zirconia thin film depositedby this method can be applied to an electrode film and a partition wallformation film between electrodes in a solid battery in a batteryindustry field.

EXAMPLES

Hereinafter, typical examples of the present disclosure will bedescribed. It goes without saying that the present disclosure is notlimited to these examples.

Example 1 SUS Substrate

Forty g of alumina powder (manufactured by SHOWA DENKO K.K.: AL-160SG-3)having an average particle diameter of 0.5 μm was put in an aluminatray, and a heat treatment was performed for 1 hour at a temperature of300° C. in the atmosphere. After that, the 40 g of alumina powder wasimmediately transferred to an aerosol-generating container formed ofglass, and the aerosol-generating container was vacuum-evacuated to notmore than 1 Pa. In order to facilitate removal of water in the powder,the aerosol-generating container was heated at a temperature of 150° C.by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 5 L/min. The alumina powder inthe aerosol-generating container (pressure; about 23 kPa) wasaerosolized, transferred by gas, and applied to a target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (having an opening of 30 mm×0.3 mm). The incidenceangle from the nozzle to the target was 60 degrees (angle inclined withrespect to the target from a vertical line by 60 degrees; the same shallapply hereinafter). The distance (space) between the tip of the nozzleand the target was 8 mm.

The powder applied to the target was deposited on a stainless steelsubstrate (having a size of 60 mm square and a thickness of 1 mm)attached to an opposed stage that is 28 mm away from the target(pressure in the deposition chamber; about 170 Pa). The target surfacewas caused to have an angle of 60 degrees with respect to the substrate(angle inclined with respect to the substrate from a vertical line by 60degrees; the same shall apply hereinafter). The drive rate of thesubstrate was 5 mm/s, and 250 films were laminated at the length of 20mm (deposition time was about 16 minutes). A transparent alumina filmhaving a film thickness of 4 μm at the center portion, a width of about37 mm, and a length of about 28 mm, was formed. The deposition shape wasa trapezoidal shape having a peripheral portion on which an interferencefringe could be seen. The film quality was dense, and the film has astrong adhesive force (which is not removed even if it is scratched byan HB pencil) to a stainless steel substrate.

The direct current electrical resistance of the formed alumina film wasmeasured. As a result, the alumina film showed an electrical resistanceof 5×10¹¹Ω. The film thickness and volume resistivity of the aluminafilm were not less than 4 μm and 1.2×10¹⁵ Ωcm, respectively. This volumeresistivity exceeded that of an alumina ceramic (bulk body; not lessthan 10¹⁴ Ωcm and not more than 10¹⁵ Ωcm).

Example 2 Si Substrate

Fifty g of alumina powder (manufactured by SHOWA DENKO K.K.: AL-160SG-3)having an average particle diameter of 0.5 μm was put in an aluminatray, and a heat treatment was performed for 1 hour at a temperature of300° C. in the atmosphere. After that, the 50 g of alumina powder wasimmediately transferred to an aerosol-generating container formed ofglass, and the aerosol-generating container was vacuum-evacuated to notmore than 2 Pa. In order to facilitate removal of water in the powder,the aerosol-generating container was heated at a temperature of 150° C.by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 10 L/min. The alumina powderin the aerosol-generating container (pressure; about 33 kPa) wasaerosolized, transferred by gas, and applied to a target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (having an opening of 30 mm×0.3 mm). The incidenceangle from the nozzle to the target was 60 degrees. The distance (space)between the tip of the nozzle and the target was 8 mm.

The powder applied to the target was deposited on a Si substrate (havinga size of half of a 2-inch wafer and a thickness of 0.5 mm) attached toan opposed stage that is 28 mm away from the target (pressure in thedeposition chamber; about 250 Pa). The target surface was caused to havean angle of 60 degrees with respect to the substrate. The drive rate ofthe substrate was 5 mm/s, and 25 films were laminated at the length of30 mm (deposition time was about 2.5 minutes). A transparent aluminafilm having a film thickness of 0.7 μm at the center portion, a width ofabout 30 mm, and a length of about 30 mm, was formed. The depositionshape was a trapezoidal shape having a peripheral portion on which aninterference fringe could be seen.

The film quality was dense, and the film has a strong adhesive force(which is not removed even if it is scratched by an HB pencil) to a Sisubstrate.

The dielectric breakdown electric field intensity of the formed aluminafilm was measured. As a result, no insulation breakdown was caused atthe center portion (having a thickness of 0.7 μm) even when a voltage of200 V was applied thereto. It was found that insulation breakdown wascaused at the peripheral portion (having a film thickness of 0.55 μm)when a voltage of 150 V was applied thereto. The dielectric breakdownelectric field intensity of the alumina film was calculated by thefollowing formula: 200 V/7×10⁻⁵ cm=2.7 MV/cm. This corresponds to notless than 10 times of that of an alumina ceramic (bulk body; 100 kV/cmto 160 kV/cm).

Example 3 Cu Substrate

Forty g of alumina powder (manufactured by SHOWA DENKO K.K.: AL-160SG-3)having an average particle diameter of 0.5 μm was put in an aluminatray, and a heat treatment was performed for 1 hour at a temperature of300° C. in the atmosphere. After that, the 40 g of alumina powder wasimmediately transferred to an aerosol-generating container formed ofglass, and the aerosol-generating container was vacuum-evacuated to notmore than 1 Pa. In order to facilitate removal of water in the powder,the aerosol-generating container was heated at a temperature of 150° C.by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 5 L/min. The alumina powder inthe aerosol-generating container (pressure; about 22 kPa) wasaerosolized, transferred by gas, and applied to a target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (having an opening of 30 mm×0.3 mm). The incidenceangle from the nozzle to the target was 60 degrees. The distance (space)between the tip of the nozzle and the target was 8 mm.

The powder applied to the target was deposited on a copper substrate(having a size of 60 mm square and a thickness of 1 mm) attached to anopposed stage that is 28 mm away from the target (pressure in thedeposition chamber; about 160 Pa). The target surface was caused to havean angle of 60 degrees with respect to the substrate. The drive rate ofthe substrate was 5 mm/s, and 250 films were laminated at the length of20 mm (deposition time was about 16 minutes). A transparent alumina filmhaving a film thickness of 4 μm at the center portion, a width of about37 mm, and a length of about 28 mm, was formed. The deposition shape wasa trapezoidal shape having a peripheral portion on which an interferencefringe could be seen.

The film quality was dense, and the film has a strong adhesive force(which is not removed even if it is scratched by an HB pencil) to acopper substrate. The direct current electrical resistance of the formedalumina film was measured. As a result, the alumina film showed anelectrical resistance of 3×10¹¹Ω.

Example 4 Glass Slide Substrate

Forty g of alumina powder (manufactured by SHOWA DENKO K.K.: AL-160SG-3)having an average particle diameter of 0.5 μm was put in an aluminatray, and a heat treatment was performed for 1 hour at a temperature of300° C. in the atmosphere. After that, the 40 g of alumina powder wasimmediately transferred to an aerosol-generating container formed ofglass, and the aerosol-generating container was vacuum-evacuated to notmore than 1 Pa. In order to facilitate removal of water in the powder,the aerosol-generating container was heated at a temperature of 150° C.by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 5 L/min. The alumina powder inthe aerosol-generating container (pressure; about 22 kPa) wasaerosolized, transferred by gas, and applied to a target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (having an opening of 30 mm×0.3 mm). The incidenceangle from the nozzle to the target was 60 degrees. The distance (space)between the tip of the nozzle and the target was 8 mm.

The powder applied to the target was deposited on a glass slidesubstrate (having a size of 50 mm×70 mm and a thickness of 1 mm)attached to an opposed stage that is 28 mm away from the target(pressure in the deposition chamber; about 160 Pa). The target surfacewas caused to have an angle of 60 degrees with respect to the substrate.The drive rate of the substrate was 5 mm/s, and 250 films were laminatedat the length of 20 mm (deposition time was about 16 minutes). Atransparent alumina film having a film thickness of 2 μm at the centerportion, a width of about 37 mm, and a length of about 28 mm, wasformed. The deposition shape was a trapezoidal shape having a peripheralportion on which an interference fringe could be seen.

The film quality was dense, and the film has a strong adhesive force(which is not removed even if it is scratched by an HB pencil) to aglass slide substrate.

Example 5 SUS Block Substrate

Fifty g of alumina powder (manufactured by SHOWA DENKO K.K.: AL-160SG-3)having an average particle diameter of 0.5 μm was put in an aluminatray, and a heat treatment was performed for 1 hour at a temperature of300° C. in the atmosphere. After that, the 50 g of alumina powder wasimmediately transferred to an aerosol-generating container formed ofglass, and the aerosol-generating container was vacuum-evacuated to notmore than 1 Pa. In order to facilitate removal of water in the powder,the aerosol-generating container was heated at a temperature of 150° C.by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 10 L/min. The alumina powderin the aerosol-generating container (pressure; about 28 kPa) wasaerosolized, transferred by gas, and applied to a target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (having an opening of 30 mm×0.3 mm). The incidenceangle from the nozzle to the target was 60 degrees. The distance (space)between the tip of the nozzle and the target was 8 mm.

The powder applied to the target was deposited on a stainless steelsubstrate (having a size of 30 mm square and a thickness of 10 mm)attached to an opposed stage that is 15 mm away from the target(pressure in the deposition chamber; about 230 Pa). The target surfacewas caused to have an angle of 60 degrees with respect to the substrate.The drive rate of the substrate was 1 mm/s, and 50 films were laminatedat the length of 30 mm (deposition time was about 25 minutes).

After that, the aerosol-generating container was returned to theatmosphere once, and 50 g of the same alumina powder obtained byperforming a heat treatment for 1 hour at a temperature of 300° C. inthe atmosphere was additionally put in the aerosol-generating container.The aerosol-generating container was heated again at a temperature of150° C. and vacuum-evacuated to 1 Pa.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 10 L/min. The alumina powderin the aerosol-generating container (pressure; about 28 kPa) wasaerosolized, transferred by gas, and applied to a new target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (having an opening of 30 mm×0.3 mm). The incidenceangle from the nozzle to the target was 60 degrees. The distance (space)between the tip of the nozzle and the target was 8 mm.

The powder applied to the target was deposited on a stainless steelsubstrate (having a size of 30 mm square and a thickness of 10 mm)attached to an opposed stage that is 15 mm away from the target(pressure in the deposition chamber; about 230 Pa). The target surfacewas caused to have an angle of 60 degrees with respect to the substrate.The drive rate of the substrate was 1 mm/s, and 50 films were laminatedat the length of 30 mm (deposition time was about 25 minutes; totaldeposition time was about 50 minutes).

An alumina film having a film thickness of 11 μm at the center portionwas formed on the entire surface of the substrate having a size of 30mm×30 mm. The film quality was dense, and the film has a strong adhesiveforce (which is not removed even if it is scratched by an HB pencil) toa stainless steel substrate. The direct current electrical resistance ofthe formed alumina film was measured. As a result, the alumina filmshowed an electrical resistance of 1×10¹²Ω.

Example 6 AlN, Cu Substrate

Thirty g of aluminum nitride powder (manufactured by TokuyamaCorporation) having an average particle diameter of 1 μm was put in analumina tray, and a heat treatment was performed for 5 hour at atemperature of 800° C. in the atmosphere. After that, the 30 g ofaluminum nitride powder was immediately transferred to anaerosol-generating container formed of glass, and the aerosol-generatingcontainer was vacuum-evacuated to not more than 1 Pa. In order tofacilitate removal of water in the powder, the aerosol-generatingcontainer was heated at a temperature of 150° C. by a mantle heater, andwas vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 5 L/min and 15 L/min. The aluminum nitridepowder in the aerosol-generating container (pressure; about 30 kPa) wasaerosolized, transferred by gas, and applied to a target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (having an opening of 30 mm×0.3 mm). The incidenceangle from the nozzle to the target was 60 degrees. The distance (space)between the tip of the nozzle and the target was 8 mm.

The powder applied to the target was deposited on a copper substrate(having a size of 60 mm square and a thickness of 1 mm) attached to anopposed stage that is 28 mm away from the target (pressure in thedeposition chamber; about 250 Pa). The target surface was caused to havean angle of 60 degrees with respect to the substrate. The drive rate ofthe substrate was 1 mm/s, and 55 films were laminated at the length of30 mm (deposition time was about 28 minutes). A brown-black aluminumnitride film having a film thickness of 2 μm at the center portion wasformed. The film quality was dense, and the film has a strong adhesiveforce (which is not removed even if it is scratched by an HB pencil) toa copper substrate.

Example 7 Circular Nozzle

Forty g of alumina powder (manufactured by SHOWA DENKO K.K.: AL-160SG-3)having an average particle diameter of 0.5 μm was put in an aluminatray, and a heat treatment was performed for 1 hour at a temperature of300° C. in the atmosphere. After that, the 40 g of alumina powder wasimmediately transferred to an aerosol-generating container formed ofglass, and the aerosol-generating container was vacuum-evacuated to notmore than 1 Pa. In order to facilitate removal of water in the powder,the aerosol-generating container was heated at a temperature of 150° C.by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 12 L/min. The alumina powderin the aerosol-generating container (pressure; about 52 kPa) wasaerosolized, transferred by gas, and applied to a target (stainlesssteel; size of 60 mm square, thickness of 0.5 mm) through a transfertubing and a nozzle (circular nozzle having an opening of φ1.6 mm). Theincidence angle from the nozzle to the target was 65 degrees. Thedistance (space) between the tip of the nozzle and the target was 8 mm.

The powder applied to the target was deposited on a copper substrate(having a size of 50 mm×70 mm and a thickness of 1 mm) attached to anopposed stage that is 28 mm away from the target (pressure in thedeposition chamber; about 240 Pa). The target surface was caused to havean angle of 65 degrees with respect to the substrate. The drive rate ofthe substrate was 2 mm/s. A process including 2 times of deposition atthe length of 30 mm in the X-axis direction and 1 time of deposition atthe length of 5 mm in the Y-axis direction was performed 6 times. Thisrepetitive deposition was performed further 3 times (deposition time wasabout 11 minutes). A transparent alumina film having a film thickness of3 μm at the center portion, a width of about 35 mm, and a length ofabout 38 mm, was formed.

The film quality was dense, and the film has a strong adhesive force(which is not removed even if it is scratched by an HB pencil) to acopper substrate. The direct current electrical resistance of the formedalumina film was measured. As a result, the alumina film showed anelectrical resistance of 2×10¹¹Ω.

Example 8 Cu Target

Thirty g of alumina powder (manufactured by SHOWA DENKO K.K.:AL-160SG-3) having an average particle diameter of 0.5 μm was put in analumina tray, and a heat treatment was performed for 1 hour at atemperature of 300° C. in the atmosphere. After that, the 30 g ofalumina powder was immediately transferred to an aerosol-generatingcontainer formed of glass, and the aerosol-generating container wasvacuum-evacuated to not more than 1 Pa. In order to facilitate removalof water in the powder, the aerosol-generating container was heated at atemperature of 150° C. by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 5 L/min. The alumina powder inthe aerosol-generating container (pressure; about 22 kPa) wasaerosolized, transferred by gas, and applied to a target (copper; sizeof 60 mm square, thickness of 0.5 mm) through a transfer tubing and anozzle (having an opening of 30 mm×0.3 mm). The incidence angle from thenozzle to the target was 60 degrees. The distance (space) between thetip of the nozzle and the target was 10 mm.

The powder applied to the target was deposited on a copper substrate(having a size of 50 mm×70 mm and a thickness of 1 mm) attached to anopposed stage that is 28 mm away from the target (pressure in thedeposition chamber; about 160 Pa). The target surface was caused to havean angle of 60 degrees with respect to the substrate. The drive rate ofthe substrate was 5 mm/s, and 250 films were laminated at the length of20 mm (deposition time was about 16 minutes). A transparent alumina filmhaving a film thickness of 4 μm at the center portion, a width of about37 mm, and a length of about 28 mm, was formed. The deposition shape wasa trapezoidal shape having a peripheral portion on which an interferencefringe could be seen.

The film quality was dense, and the film has a strong adhesive force(which is not removed even if it is scratched by an HB pencil) to acopper substrate. The direct current electrical resistance of the formedalumina film was measured. As a result, the alumina film showed anelectrical resistance of 3×10¹¹Ω

Example 9 Alumina Target

Sixty g of alumina powder (manufactured by SHOWA DENKO K.K.: AL-160SG-3)having an average particle diameter of 0.5 μm was put in an aluminatray, and a heat treatment was performed for 1 hour at a temperature of300° C. in the atmosphere. After that, the 60 g of alumina powder wasimmediately transferred to an aerosol-generating container formed ofglass, and the aerosol-generating container was vacuum-evacuated to notmore than 1 Pa. In order to facilitate removal of water in the powder,the aerosol-generating container was heated at a temperature of 150° C.by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 8 L/min and 5 L/min. The alumina powder inthe aerosol-generating container (pressure; about 22 kPa) wasaerosolized, transferred by gas, and applied to a target (alumina; sizeof 60 mm square, thickness of 0.5 mm) through a transfer tubing and anozzle (having an opening of 30 mm×0.3 mm). The incidence angle from thenozzle to the target was 60 degrees. The distance (space) between thetip of the nozzle and the target was 10 mm.

The powder applied to the target was deposited on a stainless steelsubstrate (having a size of 50 mm×70 mm and a thickness of 1 mm)attached to an opposed stage that is 35 mm away from the target(pressure in the deposition chamber; about 160 Pa). The target surfacewas caused to have an angle of 65 degrees with respect to the substrate.The drive rate of the substrate was 1 mm/s. A process includingdeposition at the length of 5 mm in the X-axis direction and at thelength of 10 mm in the Y-axis direction was performed 200 times(deposition time was about 24 minutes). A transparent alumina filmhaving a film thickness of 2 μm at the center portion, a width of about40 mm, and a length of about 25 mm, was formed.

The deposition rate was increased to 1/8 of that in the Example 1 usinga stainless steel as a target. However, the film quality was dense, andthe film has a strong adhesive force (which is not removed even if it isscratched by an HB pencil) to a copper substrate. The direct currentelectrical resistance of the formed alumina film was measured. As aresult, the alumina film showed an electrical resistance of 1×10¹¹Ω.

Comparative Example 1

Ninety g of alumina powder (manufactured by SHOWA DENKO K.K.:AL-160SG-3) having an average particle diameter of 0.5 μm was put in analumina tray, and a heat treatment was performed for 1 hour at atemperature of 300° C. in the atmosphere. After that, the 90 g ofalumina powder was immediately transferred to an aerosol-generatingcontainer formed of glass, and the aerosol-generating container wasvacuum-evacuated to not more than 1 Pa. In order to facilitate removalof water in the powder, the aerosol-generating container was heated at atemperature of 150° C. by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 20 L/min and 20 L/min. The alumina powderin the aerosol-generating container (pressure; about 94 kPa) wasaerosolized, transferred by gas, and was deposited on a stainless steelsubstrate (having a size of 60 mm square and a thickness of 0.5 mm)through a transfer tubing and a nozzle (having an opening of 30 mm×0.3mm) (pressure in the deposition chamber; about 450 Pa). The incidenceangle from the nozzle to the substrate was 60 degrees. The distancebetween the tip of the nozzle and the substrate was 19 mm. The driverate of the substrate was 1 mm/s, and 80 films were laminated at thelength of 40 mm (deposition time was about 54 minutes). A whitetransparent alumina film having a film thickness of 27 μm at the centerportion, a width of about 30 mm, and a length of about 40 mm, wasformed.

The deposition rate was 0.5 μm/min. The film quality was dense, and thefilm has a strong adhesive force (which is not removed even if it isscratched by an HB pencil) to a stainless steel substrate.

The direct current electrical resistance of the formed alumina film wasmeasured. As a result, the direct current electrical resistance of thealumina film significantly varies depending on the position of the film,and the alumina film showed electrical resistances of 10³Ω to 10¹⁰Ω. Thefilm was not suitable as an insulating film.

Comparative Example 2

Ninety g of alumina powder (manufactured by SHOWA DENKO K.K.:AL-160SG-3) having an average particle diameter of 0.5 μm was put in analumina tray, and a heat treatment was performed for 1 hour at atemperature of 300° C. in the atmosphere. After that, the 90 g ofalumina powder was immediately transferred to an aerosol-generatingcontainer formed of glass, and the aerosol-generating container wasvacuum-evacuated to not more than 1 Pa. In order to facilitate removalof water in the powder, the aerosol-generating container was heated at atemperature of 150° C. by a mantle heater, and was vacuum-evacuated.

The evacuation valve of the aerosol-generating container was closed, anda nitrogen gas for flying and transfer was adjusted by a flowmeter andwas supplied in the amount of 16 L/min and 16 L/min. The alumina powderin the aerosol-generating container (pressure; about 76 kPa) wasaerosolized, transferred by gas, and was deposited on a stainless steelsubstrate (having a size of 60 mm square and a thickness of 0.5 mm)through a transfer tubing and a nozzle (having an opening of 30 mm×0.3mm) (pressure in deposition chamber; about 370 Pa). The incidence anglefrom the nozzle to the substrate was 60 degrees. The distance (space)between the tip of the nozzle and the substrate was 19 mm. The driverate of the substrate was 1 mm/s, and 40 films were laminated at thelength of 40 mm (deposition time was about 27 minutes). A whitetransparent alumina film having a film thickness of 21 μm at the centerportion, a width of about 30 mm, and a length of about 40 mm, wasformed.

The deposition rate was 0.8 μm/min. The film quality was dense, and thefilm has a strong adhesive force (which is not removed even if it isscratched by an HB pencil) to a stainless steel substrate.

The direct current electrical resistance of the formed alumina film wasmeasured. As a result, the direct current electrical resistance of thealumina film significantly varies depending on the position of the film,and the alumina film showed electrical resistances of 10³Ω to 10⁸Ω. Thefilm was not suitable as an insulating film.

Experimental Example

Next, an experimental example of this embodiment will be described.

In this experimental example, as shown in FIG. 7, a plurality of samplesof the alumina film were prepared with different incidence angles of theaerosol injected from the nozzle 18 to the target 19 (hereinafter,referred to as angle α) and different angles of the target irradiationsurface to the substrate S on the stage 7 (hereinafter, referred to asangle β), and the film thickness and insulating properties of eachsample were evaluated. The experimental results were shown in Table 1.

It should be noted that in this experiment, the direction in which theaerosol was injected from the nozzle 18 was set to be in parallel withthe X-axis direction and the surface of the stage 7 (substrate S) wasset to be in parallel with the XY-plane. The angle α was set to theangle between the direction of the normal line of the surface of thetarget 19 and the X-axis direction, and the angle β was set to the anglebetween the direction of the normal line of the surface of the stage 7(substrate S) (Z-axis direction) and the surface of the target 19. Thedistance (NT) between the nozzle 18 and the surface of the target 19 was13 mm, and the vertical distance (TS) between the surface of thesubstrate S and the surface of the target 19 along the Z-axis directionwas 32 mm. As the target 19, the substrate S, the raw material powder,and the carrier gas, a stainless steel (SUS304) plate having a size of20 mm×7 mm, a silicon wafer, alumina particles having an averageparticle diameter of 0.4 μm, and a nitrogen gas were used, respectively.The differential pressure between the aerosol generation chamber and thedeposition chamber was not less than 26 kPa and not more than 30 kPa(flow rate of about 20 L/min).

TABLE 1 Sample 1 2 3 4 5 β (deg) 70 65 60 45 30 α (deg) 70 65 60 45 30Insulating properties x ∘ ∘ ∘ x Film thickness (μm) —  2 4.1 3.7  8

The insulating properties were evaluated in two stages. In Table 1, “x”represents that a predetermined dielectric breakdown electric fieldintensity or a predetermined direct current electrical resistance (notless than 0.2 MV/cm or not less than 1×10⁹Ω, respectively) was notachieved, and “∘” represents that the predetermined dielectric breakdownelectric field intensity or the predetermined direct current electricalresistance was achieved. It should be noted that “digital electrometer8252” (manufactured by ADCMT) and a scanning electron microscope(manufactured by Hitach, Ltd.) were used to measure the insulatingproperties and the film thickness, respectively.

As shown in Table 1, regarding samples 2 to 4 in which α and β are notless than 45 degrees and not more than 65 degrees, alumina films havingexcellent insulating properties were obtained. In addition, regardingthe samples 2 to 4, relatively high deposition rates of 200, 410, and370 (nm/min) were achieved, respectively.

On the other hand, regarding samples 1 and 5 in which α and β are 70degrees and 30 degrees, respectively, the obtained alumina films havelow insulating properties. Regarding the sample 1, it was difficult toform a film by sputtering of the surface of the substrate.

In this experimental example, α and β are set to be the same angle.However, α and β may be set to be different angles. For example, it hasbeen confirmed that an alumina film having favorable insulatingproperties is obtained under the conditions of α=40 degrees and β=60degrees.

Hereinabove, embodiments of the present disclosure have been described.However, the embodiments of the present disclosure are not limited tothe above-mentioned embodiments and various modifications can be madewithout departing from the gist of the present disclosure.

For example, in the above-mentioned embodiments, the direction in whichthe aerosol is injected from the nozzle and the in-plane direction ofthe substrate are each set to a horizontal direction. However, thesedirections are not limited thereto, and may be set to a directionvertical or diagonally to the horizontal direction.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2014-130348 filed in theJapan Patent Office on Jun. 25, 2014, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A deposition apparatus, comprising: a generationchamber configured to be capable of generating an aerosol of rawmaterial particles; a deposition chamber configured to be capable ofhaving a pressure maintained to be lower than that of the generationchamber; a transfer tubing configured to connect the generation chamberand the deposition chamber and include a nozzle configured to inject theaerosol at an end portion thereof; a target that is arranged in thedeposition chamber, has an irradiation surface that is irradiated withthe aerosol injected from the nozzle, and is configured to cause the rawmaterial particles in the aerosol to be positively charged by collisionof the raw material particles with the irradiation surface; and a stageconfigured to support a substrate on which fine particles of the rawmaterial particles generated by discharge of the charged raw materialparticles are deposited, wherein the raw material particles injectedfrom the nozzle are deflected from the irradiation surface of the targetto the substrate.
 2. The deposition apparatus according to claim 1,wherein the stage is arranged on an axis line passing through theirradiation surface of the target at an angle, the angle being between adirection of a normal line of the stage and the irradiation surface ofthe target, and the axis line being in parallel with the irradiationsurface of the target.
 3. The deposition apparatus according to claim 1,wherein the target is made of a conductive material.